1. Field of the Invention:
The present invention relates to the field of terminal pins and end caps for fluorescent discharge tubes and tube substitutes, and in particular to terminal pins which prevent and reduce electrical shock hazard.
2. Description of Prior Art:
Fluorescent discharge tubes have long been used as an economical source of artificial light. These tubes comprise elongated glass envelope tubes and contain the electrically activated, light-generating elements with end caps at the ends thereof to seal the tube and provide means for making electrical contact with the electrical elements therein. One common type of end cap is the bi-pin cap which utilizes a pair of pin terminals to connect to the corresponding lamp sockets. This type of end cap presents a shock hazard when the lamp is incorrectly installed and one end pin is left exposed out of the lamp holder. Also, if one end of an energized "hot" fluorescent tube is removed from its socket, a person inadvertently touching an exposed pin may be shocked. A hazard similarly exists with the so-called "dummy" tubes, i.e., tubes that contain no light generating elements, but rather contain simply a capacitor connecting one terminal pin at one end of the tube to the corresponding terminal pin at the other end, so as to provide electrical continuity between the lamp sockets without generating additional light. These tubes have become increasingly used in situations where a dual tube assembly is used, and when, due to energy conservation measures or the like, only the light from, and power consumption of, a single fluorescent tube is desired. A shock hazard is presented when one end of the tube is placed in the energized lamp socket and the other end is exposed; since the capacitor presents essentially a short circuit between the two pins and inadvertent contact with the exposed pin will likely cause a shock. The capacitor acts as a current limiter and the magnitude of this shock is less than that of a fluorescent lamp.
In the past, this problem has not received much attention by the lamp manufacturers, and through careful use or experience, the number of people shocked was kept to a minimum. With the increased use of the dummy tubes and the advent of consumer protection awareness, additional attention has been focused on the shock hazards. The subject invention greatly reduces the potential hazard of electrical shock, and provides a terminal pin compatible with conventional lamp sockets.